A shorthand abbreviation for the phrase "JUST SAYIN". It was originated by teenage girls for use in instant messages and text messaging, but has since been adopted by a very small segment of grown men that are still trying to hold on to their youthful qualities and adolescent absurdity. The use of this phrase has also been used to locate those with casting potential on news specials hosted by Chris Hansen.

When carrying on a conversation with a grown man, he actually responded to something that I said with the following "JS man JS". WTF does that mean?

js, or "j.s." is short for "just saying." It's a shortening of the word for texting but is also used in everyday language, just as "omg" has become. It is usually used at the end of a sentence, and commonly in a sentence where you are making a rude or mean comment. You're "just sayin," so no matter what you say, the other person shouldn't get mad, it's more of a joke.

Instead of saying, "not to be rude, but Ann is a real bitch" you say, "Ann is a real bitch, js."

Your friend will get mad if you say, "you're being a douche."
But if you say, "you're being a douche, js." it's more like your informing him rather than insulting him, in a lighter tone.